The invention relates to a macrolens assembly with a lens mount including a lens system, and in which is rotatively supported a distance setting ring with a scale mounted coaxially to the lens axis.
In macrolenses it has been conventional to set the focus distance using a distance setting ring. Because it is necessary to design the distance setting ring in such a way that it can be rotated more than 360.degree. , it is a common practice to make the distance scale in different colors placed opposite to a multicolored index mark. This creates the problem that the colors must be assigned correctly when setting the distance setting ring. Faulty focusing becomes possible especially when trying to quickly set the lens with relatively little concentration. This also provides difficulty under poor light conditions, because of the reduced color perception of the human eye.
In recognition of this problem, the present invention has as its object the provision of a macrolens with which with relatively little increased technical effort the distances can be set with precision throughout the entire range.
According to the invention, this object is achieved by providing at least two distance setting rings arranged inside the mount and fitted into each other. Only the radially innermost distance setting ring is guided from exteriorly of the mount, through an annular opening therein, to form a driving ring. The distance setting rings adjacent to the innermost distance setting ring are rotatively connected to the innermost distance ring by means of a driver that can be automatically released by a radial pressure. Both the lens mount and the distance setting rings adjacent to the radially innermost distance setting ring are each provided with a control window. Transition and easy changing from one distance setting ring to the next is possible with this solution, which uses a relatively simple design. In this way, only one distance measurement is ever visible from the control window, this distance being always advantageously assigned to the index mark. Thus faulty settings are harder to make, even if the distance setting ring is activated hastily and with little concentration.
Another advantage is that a more practical gradation of colors of the distance range becomes now possible. For example, the distance setting rings in the range from infinite to one meter may be colored blue, green in the adjoining range, and red in the very special macrorange. This makes very fast spotting of the desired distance range possible, followed by an accurate focusing.
An advantageous modification of the invention consists in providing one stop each on the radially innermost distance ring, on its radial exterior and on the interior of the mount, which stops are staggered towards each other in a tangential direction at a distance corresponding to the tangential width of the control windows, whereby the driver connected to the second distance setting ring is provided between these two stops. The start of the distance scale on the radially outer ring is provided with this construction. The latter is carried along by the driver from the radially inner distance setting ring, which can be rotated by the driving ring provided on the exterior mounts. After a 360.degree. rotation minus the tangential width of the control window there appears in the radially outer distance ring another control window, so that the scale on the radially inner distance ring now becomes visible. The radially outer distance ring is held in position by the stop of the driver on the stop connected to the interior of the mount, and the distance scale continues smoothly on the inner distance ring.
According to the invention, the control windows in another preferred embodiment of the invention are staggered one directly behind the other in the direction of the radial exterior of the distance rings for the installation of the scale.
According to another advantageous variant of the invention, provision is made for the construction of the driver as a ball catch, which acts bilaterally in the radial direction and which, in the initial position of rotation determined by the contact of the two stops with the driver, locks into a first notch of the radially innermost distance ring, and into another notch provided on the interior of the mount is staggered in relation to the first notch at a tangential distance corresponding to the width of the control windows. In this way, the initial position of the driving ring is fixed by a non-passable stop. Thus, the activation of the driving ring for distance setting is possible in only one direction, whereby the stop of the radially inner distance ring is moved away from the stop of the lens mount. By appropriately spacing the two notches from each other, it is ensured that, after one rotation, the control window of the radially outer distance ring is located exactly beneath the control window arranged in the lens mount.
According to another embodiment of the invention, the driver may advantageously be formed as a permanent magnet, which, together with its pole pieces, is connected to the distance ring adjacent to the mount and cooperates with air guides from ferromagnetic material, which are mounted on the stops connected to the interior of the mount, or to the radially innermost distance ring. Such a notch-free driver is relatively simple to make and is practically trouble-free.
Finally, another advantageous embodiment of the invention is obtained by providing three distance rings, each of which is rotatively connected by means of drivers to the radially innermost distance ring. Such a structural approach makes an extremely high scale resolution possible, so that a highly accurate distance setting can be carried out.